Light non-inflammable laminates

ABSTRACT

Non-inflammable laminates which on combustion give only small and non-toxic amounts of fumes and gases have a thin metal foil facing on an asbestos paper support and a core of glass fibre fabric, polyamide-imide fibre fabric, or polyimide fibre fabric, optionally with an asbestos fabric, the whole being bonded together with an organosilicon polymer or polyimide.

United States Patent 1 Ravel Oct. 30, 1973 LIGHT NON-INFLAMMABLELAMINATES [75] Inventor: Jean Ravel, Lyon, France [73] Assignee:Rhone-Poulenc S.A., Paris, France [22] Filed: May 23, 1972 [21] Appl.No.2 256,040

[30] Foreign Application Priority Data May 25, 1971 France 7118854 [52]US. Cl. 161/79, 161/84, 161/93, 161/98, 161/205, 161/403, 161/182,

[51] Int. Cl B321) 5/00 [58] Field of Search 161/79, 82, 84, 85, 161/93,156, 205, 213, 224, 403

[56] References Cited 7 UNITED STATES PATENTS 3,231,451 111966 Gazelle161/205 3,677,882 7/1972 Jahns 161/403 2,561,891 7/1951 Tucker 161/4033,700,538 10/1952 Kennedy [61/403 Primary Examiner-George F. LesmesAssistant ExaminerJames J. Bell Attorney-Richard K. Stevens et a1.

[5 7] ABSTRACT Non-inflammable laminates which on combustion give onlysmall and non-toxic amounts of fumes and gases have a thin metal foilfacing on an asbestos paper support and a core of glass fibre fabric,polyamide-imide fibre fabric, or polyimide fibre fabric, optionally withan asbestos fabric, the whole being bonded together with anorganosilicon polymer or polyimide.

8 Claims, 3 Drawing Figures PATENTEDHBIQO m 3.769.146

LlGl'ilT NON=KNFLAMMABLE LAMINATES The present invention relates tolightweight, noninflammable laminates.

The losses of human lives in fires which have occurred unexpectedlyeither in vehicles (e.g., aeroplanes, boats and land vehicles) or inpublic places (e.g., department stores, cinemas and theatres) have ledthose responsible for public safety to make stringent regulationsrelating to materials used in such vehicles and places, especially inrespect of their non-inflammability, the amount of fumes they produce oncombustion and the nontoxicity of the by-products of pyrolisis. The useof inorganic substances for materials which must meet these criteria isacceptable for terrestrial installations where weights are of secondaryimportance compared with cost. For aerial transport, however, the weightmust be as low as possible especially in structures which do notcontribute to the pay load.

The present invention provides a non-inflammable laminate weighing lessthan about 2,800 g./m comprising a metal foil facing less than 50microns thick, an asbestos paper support for said metal foil facing, anda core comprising one or more layers of a glass fibre fabric, apolyimide-amide fibre fabric, or a polyimide fibre fabric and optionallyin addition of an asbestos paper or asbestos felt, which paper or feltis unreinforced or reinforced with glass fibres, all the nonmetalliclayers of the laminate being bonded together with an organosiliconpolymer binder or with a polyimide binder. Such laminates, oncombustion, evolve only very small and non-toxic amounts of fumes andgases.

The weight of the new laminates naturally varies with their thickness.Thus when the laminates are 1 mm. thick, and are to be used inaeronautics, their weight preferably does not exceed about 1,600 g/m(generally the requirement is that the weight should be from 800 to1,400 glm i.e., their density is preferably not above 1.6 g./cm.

The organosilicon polymers which may be used as binders are commonlyavailable resins, which are sold commercially either dissolved insolvents or undiluted. They are described, for example, in French Pat.No. 1,568,812. The polyimide binders, which are well known to have goodheat resistance, are described in, for example, French Pat. Nos.1,365,545 and 1,555,564.

Suitable metal foils are of, for example, aluminium, stainless steel,copper, titanium and alloys of these metals. Their thickness should notexceed a few tens of microns and, at most, 50 microns. They are glued tothe asbestos paper supports by conventional glues, for example, thosebased on alkali metal silicates or on organic orthosilicates.

The new laminates are prepared by the usual techniques. The materials,impregnated with the binders, are stacked in a mould and then heated attemperatures and under pressures, which depend on the nature of thebinders used. However, low pressures, slightly greater than 1 bar, andtemperatures in the region of 150C. lead to good results even after onlya comparatively short period of time and can be used in appropriatecircumstances. The thickness of the laminates obtained is obviously afunction of the thickness of the materials, their number, and the amountof binders used. Howparts ever, in order that these laminates, composedof layers of dense substrates and of binders, should weigh not more than1,600 g./m for a thickness of 1 mm., the amount of binder is chosen soas not to exceed this limit. in general, the percentage by weight of thebinder, based on the weight of the laminate, is from 5 to 60 percent,but it is preferably 15 to 35 percent, taking account of therequirements'imposed on the laminates.

The laminates of the invention can be machined by any of the commonmethods of cutting and piercing. Furthermore, their surfaceimpermeability allows periodic cleaning with sponges or scraper spongessoaked in aqueous solutions of a wide range of detergents and theiruniformity in colour makes unnecessary the application of colouredpaints or of decorative plastic films, though such can be applied ifdesired.

They can be used in all fields where there is need for materials whichare non-inflammable and which evolve only a small amount of non-toxicfumes and gases at temperatures greater than 1,000C. They are, however,especially suitable for masking the heat insulations of the cabins andstorage spaces of aeroplanes and for being fixed by screws onto thetransverse members and longitudinal struts of the cabins or onto theframes of the storage spaces.

The following Examples illustrate the invention.

EXAMPLE 1 A laminate as shown in FIG. 1 of the accompanying drawings isprepared by superposing, in a first stage, on a metal plate which haspreviously been coated with a non-stick agent, flat materials, thedimensions of which are slightly less than 40 X 40 cm, impregnated withorganosilicon polymers.

This impregnation is carried out by immersion for about 15 minutes in abath consisting of (the parts being by weight): methylpolysiloxane resinwith Cl l -,Si0, units 20 parts ethyl silicate 8.3 parts 5 pe censqueals i i/$921929 as dssl t sne L methanol parts followed byevaporation of the solvent by passage through a ventilated oven, heatedto C.

The order of a superposition and the nature of the materials used are asfollows: 1.

A paper of chrysolite asbestos fibres 1 on one face of which there isglued a thin aluminium foil 2, this metallised face being in contactwith the metal plate of the mould. This assembly, hereafter called theasbestosaluminium complex, weighs 280 g/m. 2.

A degreased glass fabric 3 of the satin type, weighing 87 g/m.

A paper of chrysolite asbestos fibres l weighing 200 g/m. 4.

A glass fabric 3 like that mentioned under (2). 5.

An asbestos-aluminium complex like that already used under (1), themetallised face being towards the outside.

In a second stage, the stack is covered by another metal plate, the faceof which, resting on the materials, is also coated with a non-stickreagent. The mould, formed in this way, is placed between the platens ofa press. The press is closed and the mould is held at 250C. for 90minutes under a pressure of 80 kg/cm. A 1 mm. thick laminate is obtainedwhich weighs 1,230 g/m and contains about 25'percent by weight oforganosilicon polymers.

It satisfies the tests laid down first by Standard SpecificationN.P.R.M. 6933 relating to the non-inflammability and secondly byStandard Specification N.P.R.M. 6930 relating to the evolutions of smallamounts of non-toxic fumes and gases. These Standard Specifications werepublished in July, 1970 by Department of Transportation of the AmericanAviation Association.

The laminate is thus non-inflammable and, when strongly heated, evolvesonly very small amounts of fumes and gases which are not dangerous.Furthermore, it can be machined easily.

EXAMPLE 2 A laminate, as shown in FIG. 2, is prepared by following theprocedure of stacking of Example 1'. Before being superimposed, thematerials are impregnated with organosilicon polymers by immersion in asolution of resin having the following composition (the parts being byweight): organopolysiloxane resin consisting of (CI-1;),Si0 and C I-lSiO units in the ratio 1/3 parts toluene 76.6 parts choline octoate 2parts zinc octoate 1.4 parts followed by evaporation of the solvent bypassage through a ventilated oven heated to 110C.

The order of superposition and the nature of the materials are asfollows:

The asbestos-aluminium complex used in Example 1, weighing 280 g/m, themetallised face 2 being in contact with the plate of the mould.

A degreased glass fabric 5 of the satin type, weighing 55 g/m.

A felt of asbestos 4, reinforced with glass filaments 6, weighing 320g/m.

A glass fabric Slike that used under (2).

A felt of asbestos 4 like that used under (3).

A glass fabric 5 like that used under (2). 7.

The asbestos-aluminium complex of the type used under (1), themetallised face 2 being turned towards the outside.

The whole is then heated at 150C. for 1 hour 30 minutes, under apressure of 10 kg/cm. The 1.5 mm. thick laminate obtained weighs 1,600g/m and contains about 17 percent by weight of organosilicon poly mers.it satisfies the tests laid down by the Standard Specifications N.P.R.M.6933 and 6930 and is easy to cut up and to pierce with holes.

EXAMPLE 3 A laminate is prepared by the stacking technique described inExample 1. Before being superposed, the materials are impregnated with afluid organopolysiloxane polymer, catalysed by 1.5 percent of its weightof dicumyl peroxide, of viscosity 10,800 cSt at 20C., Consisting OfceHgsiog a, (CaH5)gSiO, CH,(Cl-l =Cl-l)SiO, (Cl-1 SiO and (CHQ SiO unitsin the respective ratio 10/35/40/8/7.

The order of superposition and the nature of the materials are asfollows:

An asbestos-aluminium complex like that used in Example 1, but weighing280 g/m, the metallised face being in contact with the plate of themould.

Two degreased glass fabrics, each weighing 308 g/m*. 3.

An asbestos-aluminium complex like that used under (1) the metallisedface being turned towards the outside.

The assembly is then heated at C. for 1 hour under a pressure of 10kg/cm. The 1 mm. thick laminate obtained weighs 1,550 g/m and contains26 percent by weight of organosilicon polymer. It has a flex- .uralstrength, measured in accordance with Standard Specification A.S.T.M.790-63, of 8.5 kg/mm and a tsststtsq lbp l ks- Furthermqre, it sa sfithe aquirements of Standard Specifications N.P.R.M. 6933 and 6930.

To measure the tear strength, a 5 mm. diameter hole is pierced in asample of the laminate near one edge, the edge of the hole being at itsnearest point, 5 mm. from the edge of the laminate. A metal rod which isfirmly fixed to the movable part of a tensometer is threaded into thehole and the part of the sample opposite the hole is held between thefixed jaws of the tensometer. The movable part is then caused to travelat a speed of 14 mm. per minute until the sample tears at the hole. Atthis moment, the tensometer records the tear strength, which is found tobe 17 kg.

EXAMPLE 4 A laminate as shown in FIG. 3 is prepared by following thestacking procedure of Example 1. Before being superposed, the materialsare impregnated with anorganic prepolymer by immersion in a solutionhaving the following composition (the parts being by weight):prssolimsta asdhuhea sst srtss N .1S'-4.4- diphenylmethane-bis-maleimidewith 8.29 parts of bis- (4-amino-phenyl)-methane for 1 hour at 120C.-45parts N-methylpyrrolidone 38.5 parts xylene 16.5 parts followed byevaporation of the solvents by passage through a ventilated oven, heatedto C.

The order of superposition and the nature of the materials are asfollows:

A paper of chrysolite asbestos fibres 1 on one face of which-is glued athin stainless steel foil 8, this metallised face being in contact withthe metal plate of the mould. The complex weighs 264 g/m.

Three fabrics 9 of polyimide-amide fibres, each weighing 90 g/m. 3

A paper of chrysolite asbestos fibres 1 on one face of which is glued athin copper foil 7, this metallised face being towards the outside ofthe stack. This complex weighs 246 g/m.

The assembly is then heated for 1 hour at 180C., under a pressure ofkglcm followed by 24 hours at 250C. in a ventilated oven. The 0.9 mm.thick laminate obtained weighs 1,014 g/m and contains about 23 percentby weight of polyimide binder; it satisfies the tests laid down byStandard Specifications N.P.R.M. 6933 and 6930 and can be machinedeasily.

I claim:

1. A non-inflammable laminate weighing less than about 2,800 g/mcomprising a metal foil facing less than 50 microns thick, an asbestospaper support for said metal foil facing, and a core comprising one ormore layers of a glass fibre fabric, a polyimide-amide fibre fabric, ora polyimide fibre fabric and optionally in addition of an asbestos paperor asbestos felt, all the non-metallic layers of the laminate beingbonded together with an organosilicon polymer hinder or with a polyimidebinder.

2. A laminate according to claim 1 having on both faces a said metalfoil facing with an asbestos paper support.

3. A laminate according to claim 1 in which the core comprises twolayers of glass fibre fabric having an asbestos paper sandwichedtherebetween.

4. A laminate according to claim 1 in which the core comprises threelayers of glass fibre fabric alternating with two layers of asbestosfelt reinforced with glass fibres.

5. A laminate according to claim 1 in which the core comprises twoadjacent layers of glass fibre fabric.

6. A laminate according to claim 1 in which the core comprises threeadjacent layers of a polyamide-imide fibre fabric.

7. A laminate according to claim 1 having a density not above 1.6 g/cm8. A laminate according to claim 1 comprising 15 to 35 percent by weightof the said binder.

* h i i

2. A laminate according to claim 1 having on both faces a said metalfoil facing with an asbestos paper support.
 3. A laminate according toclaim 1 in which the core comprises two layers of glass fibre fabrichaving an asbestos paper sandwiched therebetween.
 4. A laminateaccording to claim 1 in which the core comprises three layers of glassfibre fabric alternating with two layers of asbestos felt reinforcedwith glass fibres.
 5. A laminate according to claim 1 in which the corecomprises two adjacent layers of glass fibre fabric.
 6. A laminateaccording to claim 1 in which the core comprises three adjacent layersof a polyamide-imide fibre fabric.
 7. A laminate according to claim 1having a density not above 1.6 g/cm3.
 8. A laminate according to claim 1comprising 15 to 35 percent by weight of the said binder.